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Index of Subjects Hi, Birds can't read, so how should they know what they are supposed to do or not to do? Here we have one more example....... ;) We have seen some considerable changes in species distribution ranges in the past two decades. After all the oystercatchers on CSI established themselfes only in the late 1990s. Changing behaviour from non-migratory to migratory is very dramatic and requires much longer time periods than just expanding /changing distribution ranges by a few kms a year. Here lies the catch why a number of long range migrants will have problems adjusting their life cycle to global warming associated shifts in seasonal timing in their extreme breeding areas. Evolution has no time to keep the pace, and as a result evolution will cause at least some populations of such species to disappear because they arrive virtually to late to get their business done in time. A quick check in the literature shows that oystercatchers (American, Black, Eurasian) are indeed migratory, and are known to have followed this habit for considerable time (i.e. much longer than 1996). The catch, and an excuse for the author, is that populations that live in favourable habitats can be non-migratory or "move just around the corner" when season changes. The Florida population of A. Oystercatchers is an example, and I guess that the Black Oystercatchers in parts of California also stay put year round. Same applies to their european relatives in the mediteranean. Those populations found breeding on the more extreme edges of the species' geographical range have not much choice than heading south, considering seasonal weather changes in Alaska, the Aleutes, Sibiria, Iceland, Northern Europe etc. that are well in their range. Such behavioural differences between subpopulations are known for many bird species, and even within a geographical area a mix of migratory and non-migratory individuals during the breeding season is common. How much of this could have been known by Harry Thurston when he wrote the book? Well, I wouldn't consider this particular book not a reference in the scientific sense ...... Ulli > Hi all: > > I'm currently reading Shorebirds - Nomads of the Wetlands, by Harry Thurston. This > book was written in 1996 and I assume that quite a bit has changed since it came out on > the market. I've come across a number of things now that I would questions or double > check before I would except them as a give.One that really sticks out for me is on page > 51, where he states that oystercatchers are nonmigratory. We know that the American > oystercatchers that are found at Cape Sable Island are certainly migratory and that > some occasionally show up in other areas of Nova Scotia. So is this something that has > changed since the book was written? > > James R. Hirtle > Bridgewater
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